In order to meet wireless data traffic demands that have increased after the commercialization of 4th Generation (4G) communication system, efforts to develop an improved 5th Generation (5G) communication system or a pre-5G communication system have been made. For this reason, a 5G communication system or a pre-5G communication system is referred to as a beyond 4G network communication system or a post long term evolution (LTE) system.
In order to achieve a high data transmission rate, implementation of the 5G communication system in an ultra-high frequency (mmWave) band (for example, 60 GHz band) is being considered. In the 5G communication system, technologies such as beamforming, massive Multi-Input Multi-Output (massive MIMO), Full Dimensional MIMO (FD-MIMO), an array antenna, analog beam-forming, and a large scale antenna are discussed in order to mitigate a propagation path loss in the mmWave band and increase a propagation transmission distance.
Further, technologies such as an evolved small cell, an advanced small cell, a cloud Radio Access Network (cloud RAN), an ultra-dense network, Device to Device communication (D2D), a wireless backhaul, a moving network, cooperative communication, Coordinated Multi-Points (CoMP), and interference cancellation have been developed to improve the system network in the 5G communication system.
In addition, the 5G system has developed Advanced Coding Modulation (ACM) schemes such as hybrid FSK and QAM Modulation (FQAM) and Sliding Window Superposition Coding (SWSC), and advanced access technologies such as Filter Bank Multi Carrier (FBMC), Non Orthogonal Multiple Access (NOMA), and Sparse Code Multiple Access (SCMA).
Meanwhile, communication systems are continuously under development with the aim of improving throughput, and latency functions as a very important variable in improving throughput.
In the next generation communication system, an ultra-realistic service is under discussion, and a very short latency is required in the ultra-realistic service. As an example of the latency required in the ultra-realistic service, the latency required for a sense of pain is 1 second, the latency required for an auditory sense is 100 milliseconds, the latency required for vision is 10 milliseconds, and the latency required for a tactile sense is 1 millisecond. In the next generation communication system, a data rate is expected to increase sharply.
In most cases, a transmission control protocol (TCP) is used as a transmission layer between a terminal and a server providing a service to the terminal. However, the TCP has a limitation in reducing the latency due to the characteristics of the TCP itself. For example, assuming that TCP uses a window scheme for a flow control, the terminal transmits data corresponding to a predetermined window size and also gradually increases the size of data to be transmitted as the window size increases. However, when the transmitted data is corrupted or an error occurs, the TCP halves the window size to control the data rate, so as to increase the latency of the transmission layer.
Therefore, it is important to reduce the latency of the transmission layer in order to satisfy the latency required in the next generation communication system, and studies on reducing the latency of the transmission layer are needed.